Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 290759 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 359 AM EDT MON JUN 29 2015 .SYNOPSIS... HIGH PRESSURE OVER VIRGINIA THIS MORNING WILL WEAKEN THROUGH THE REMAINDER OF TODAY. A LOW PRESSURE SYSTEM OVER ILLINOIS WILL MOVE EAST INTO OHIO TONIGHT AND THEN CROSS LAKES ERIE AND ONTARIO ON TUESDAY...PUSHING A WARM FRONT NORTHEAST ACROSS OUR AREA. A COLD FRONT WILL THEN PUSH SOUTHEAST ACROSS THE AREA ON WEDNESDAY BEFORE STALLING IN THE AREA ON THURSDAY THROUGH SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... SFC LOW PRESSURE MOVING OFF THE COAST OF MAINE EARLY THIS MORNING...WITH HIGH PRESSURE BEGINNING TO MOVE IN FROM THE SOUTH. THERE IS STILL A BIT OF GRADIENT...AND COMBINED WITH THE DRY AIRMASS...EXPECT ANY FOG TO BE ISOLATED. CENTER OF HIGH PRESSURE SLIDES BY TO THE SOUTH TODAY. RETURN FLOW DOESN/T RETURN UNTIL LATE IN THE DAY...SO HIGH TEMPERATURES WILL REMAIN BELOW NORMAL...IN THE UPPER 70S TO LOWER 80S...PERHAPS SOME MID 80S EAST. THERE ARE SOME ISOLATED SHOWERS IN THE OHIO VALLEY AND THIS ISENTROPIC LIFT COMBINED WITH SHORTWAVE ENERGY BRUSHING BY WILL MOVE TOWARD THE MOUNTAINS LATE IN THE DAY. HELD OFF ANY POPS UNTIL EVENING...AND EVEN THEN KEPT AT SLIGHT CHANCE. LOW PRESSURE PIVOTS TOWARD LAKE ERIE TONIGHT...WITH AN EFFECTIVE WARM FRONT LIFTING ACROSS THE AREA. BEST LIFT AND MOISTURE WILL BE ACROSS WESTERN AREAS...EVENTUALLY SPREADING EAST ACROSS THE MASON- DIXON LINE. STILL NOT EXPECTING MUCH MORE THAN ISOLATED/SCATTERED SHOWERS HOWEVER...AS MAIN ENERGY WILL BE FOCUSED NORTH OF THE AREA. LOW TEMPERATURES WILL CREEP BACK UP INTO THE 60S AS SLIGHTLY HIGHER DEW POINTS RETURN. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... THE REGION WILL BE IN THE WARM SECTOR OF A LOW PRESSURE SYSTEM MOVING THROUGH THE LOWER GREAT LAKES ON TUESDAY. MID AND UPPER TROUGH AXIS WILL BE LOCATED WEST OF THE AREA...BUT IMPULSES WITHIN THE FLOW WILL MOVE ACROSS THE AREA TO COMBINE WITH DIURNAL INSTBY TO PRODUCE SHOWERS AND STORMS. ACTUAL FRONT DOES NOT PUSH IN FROM THE WEST UNTIL EVENING...SO TERRAIN ALSO WILL PLAY A ROLE. THINK COVERAGE WILL BE FAIRLY LIMITED UNTIL MID AFTERNOON. DEEP LAYER SHEAR EXPECTED TO BE AOA 30 KT. AMOUNT OF INSTBY SHOULD BE ON THE LOWER END OF THE SPECTRUM...BUT COULD BE ENOUGH FOR SOME STRONGER STORMS TO DEVELOP. A MARGINAL RISK FOR SEVERE WX CONTINUES. TEMPERATURES RETURN CLOSER TO NORMAL...MID 80S TO AROUND 90. WARM FRONT WILL ADVANCE NORTHEAST ACROSS THE AREA TUESDAY NIGHT AS LOW PRESSURE TO THE NORTH PUSHES EASTWARD. DECENT CAPE AND SHEAR PRESENT AS A SHORTWAVE APPROACHES FROM THE WEST...SO THERE IS THE RISK OF SOME SEVERE WX IN THE EVENING BEFORE THE END OF INSOLATION ALLOWS CAPE TO WANE. THE LOW DRAGS A COLD FRONT SOUTHEAST INTO THE AREA WEDNESDAY WHICH STALLS OUT WEDNESDAY NIGHT. SEVERE PARAMETERS DON`T LOOK AS GOOD BY WEDNESDAY AFTERNOON WITH A BIT TOO MUCH OF A DRY LAYER AND LESS SHEAR...SO PROBABLY LESS RISK OF SEVERE WEATHER DESPITE THE STALLING FRONT...ESPECIALLY SINCE THE SHORTWAVE LOOKS TO HAVE CLEARED THE CWA BY MID AFTERNOON. TEMPERATURES WILL LIKELY SPIKE A BIT JUST AHEAD OF THE FRONT AND A FEW 90S CAN`T BE RULED OUT IN THE HOTTEST SPOTS. WITHOUT GOOD FORCING ALOFT...MOST OF WEDNESDAY NIGHT WILL TURN OUT DRY. && .LONG TERM /THURSDAY THROUGH SUNDAY/... THE FRONT APPEARS TO STALL OUT ACROSS THE GENERAL VICINITY FOR MOST OF THE LONG TERM...WITH MULTIPLE DISTURBANCES MOVING QUICKLY EAST ACROSS THE AREA IN THE WESTERLY FLOW ALOFT. THIS WILL KEEP THE WEATHER RELATIVELY UNSETTLED WITH LITTLE CHANCE OF HIGH HEAT BUT ALSO NOT A GREAT CHANCE OF SUSTAINED DRY WEATHER. INDIVIDUAL SHORTWAVE ORIENTATION AND FRONT POSITIONS WILL DICTATE ANY THREATS OF SEVERE WEATHER OR FLOODING...BUT THE RISK IS NOT ZERO. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... RECENT TRENDS SUGGEST ANY FOG DEVELOPMENT EARLY THIS MORNING SHOULD BE ISOLATED AND UNLIKELY TO AFFECT TAF SITES. VFR THROUGH TODAY UNDER HIGH PRESSURE...WITH LIGHT WINDS GRADUALLY TURNING FROM WEST TO SOUTH BY LATE AFTERNOON. FAIRLY HIGH PROBABILITY OF VFR THROUGH TONIGHT AS WELL ALTHOUGH MID LEVEL CIGS DEVELOP AHEAD OF LOW PRESSURE. SOUTHERLY WINDS INCREASE A BIT TUESDAY...WITH A FEW GUSTS TO 20 KT POSSIBLE. SCATTERED THUNDERSTORM ACTIVITY WILL BE MOST LIKELY FROM MID-AFTERNOON ONWARD...WITH THE POTENTIAL FOR MVFR/IFR CONDITIONS AND STRONG WIND GUSTS. OVERALL VFR THROUGH THE REMAINDER OF THE WEEK AND WEEKEND...HOWEVER THE THREAT OF THUNDERSTORMS WILL PERSIST EACH DAY WITH ANY STORM CAPABLE OF BRIEF IFR CIGS/VIS...GUSTY WINDS...AND HAIL. SOUTHWEST WINDS AHEAD OF A COLD FRONT WEDNESDAY WILL BECOME MORE VARIABLE LATER IN THE WEEK AS A FRONT LINGERS ACROSS THE REGION. && .MARINE... WINDS ARE GRADUALLY DIMINISHING OVER THE WATERS EARLY THIS MORNING. SCA WILL BE EXPIRING AND LIGHT SOUTHWESTERLY FLOW WILL CONTINUE TODAY AS HIGH PRESSURE MOVES BY TO THE SOUTH. SOUTHERLY FLOW MAY BEGIN TO CHANNEL OVER THE BAY TONIGHT...BUT STILL LOW CONFIDENCE ON WHETHER THIS WOULD REACH SCA LEVELS. WINDS WILL INCREASE TUESDAY AS LOW PRESSURE APPROACHES FROM THE WEST...AND SCA HAS BEEN ISSUED FOR ALL THE WATERS. THUNDERSTORM CHANCES INCREASE DURING THE MID TO LATE AFTERNOON HOURS AND COULD CONTAIN STRONG WIND GUSTS. MAY HAVE ISSUS WITH SCA CONDITIONS WEDNESDAY AS THE NEXT COLD FRONT SLIDES SOUTHEAST INTO THE AREA. AFTER THAT...THE FRONT WILL LINGER IN THE AREA AND INTERMITTENT SCA CONDITIONS WILL BE POSSIBLE AS INDIVIDUAL SYSTEMS RIDE ALONG THE FRONT. THE THREAT OF SHOWERS AND THUNDERSTORMS...WHILE NOT PARTICULARLY HIGH ANY DAY JUST YET...WILL NOT COMPLETELY GO AWAY THANKS TO THE PRESENCE OF THE FRONT THROUGH MOST OF THE LONG TERM. && .HYDROLOGY... ALL FLOODING HAS ENDED AND ALL FLOOD WARNINGS HAVE BEEN CANCELLED OR ALLOWED TO EXPIRE. HEAVY RAINS ARE NOT ANTICIPATED AT LEAST FOR THE NEXT SEVERAL DAYS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR ANZ532-533-537-540>542. SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ534-543. && $$ SYNOPSIS...RCM NEAR TERM...ADS SHORT TERM...ADS/RCM LONG TERM...RCM AVIATION...ADS/RCM MARINE...ADS/RCM HYDROLOGY...RCM

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